Building a new Computer!

Ok so as the title says im going to be building a new computer, budget it around £450 which is around $700. So what sort of computer could i put together with this amount of money, not including monitor, keyboard and mouse. Just the tower itself, to give me idea, wat sort of wow setting would i be running on with the budget ive stated? Put things into perspective the best you can to try to get me to undersdtand how good it would be :P Cheers!